The obtainable density of DRAM and other semiconductor devices is strongly tied to the ability to miniaturize their component structures, among them capacitors. In turn, thinner and smaller area capacitors are obtained using high dielectric constant materials. Certain metal oxides show promising application as these high dielectric constant materials, but these metal oxides can vary greatly in terms of obtainable and reproducible dielectric constant. What is more, some of these oxides can produce greater charge leakage than other materials, which becomes an increasingly important consideration as the layer size and capacitor size shrink. In order to produce higher density capacitors and other semiconductor devices, it is desired to have designs based on high dielectric constant, low leakage (i.e., low effective oxide thickness) materials.
Zirconium oxide (ZrO2) has been used as a capacitor dielectric in some designs, typically in substantially amorphous form, heavily doped with aluminum to help suppress leakage. However, as process technologies become increasingly small, the dielectric constant and equivalent oxide thickness (“EOT”) provided by this zirconia-based film are not sufficiently robust. The use of amorphous as opposed to crystalline films and the conventional use of an aluminum dopant can limit these parameters to the point where amorphous zirconium oxide can be unsuitable for process technologies below 60 nanometers.
A need therefore exists for ways to effectively produce high dielectric constant zirconium oxides; ideally, such methods could be inexpensively implemented in a manufacturing context; this would lead to consistently higher dielectric constant and low leakage, and therefore greater, reproducible device density. The present invention addresses these needs and provides further, related advantages.
The invention defined by the enumerated claims may be better understood by referring to the following detailed description, which should be read in conjunction with the accompanying drawings.